Concerning the image forming apparatuses controlled by the dry electro-photographic method, electrostatic latent images formed on a photoconductor are developed by toner to be toner images, wherein said toner images are, directly or through an intermediate transfer body, transferred onto a recording sheet. After that, the toner particles remaining on the surface of the photoconductor are removed by a cleaning device. Toner particles tend to fly or drop during the development process, transfer process, and cleaning process, which cause pollution within the apparatus, so that such pollutants have become a major problem.
To overcome the flying or dropping toner particles, Patent Document 1 discloses a technology, in which a suction hole for the flying toner particles is provided on an outlet of the developing device, and the suctioned toner particles are filtered by a filter to be collected. Since the filter is exchangeable, a clogged filter is exchanged for new one.
However, in large and high-speed image forming apparatuses, there are a large number of flying toner particles or dropping toner particles (hereinafter, referred to as “flying toner particles”), so that the structure to collect the flying toner particles by the filter as shown in Patent Document 1 tends to result in a clogged filter to be exchanged. In order to exchange the clogged filter, the service person is requested to visit an office having the large and high-speed image forming apparatuses, which results in low productivity.
Further, Patent Document 2 discloses that ducts are provided on an inlet and an outlet of the developing device, and the flying toner particles, suctioned by these duct, are classified through a cyclone separator into toner particles, exhibiting predetermined large sizes to be used again, and toner particles, exhibiting undesired sizes, whereby the toner particles, to be used again, are returned to the developing device, and the toner particles, exhibiting undesired sizes, are sent to a filter.
Still further, since the flying toner particles are created in the cleaning device, Patent Document 3 discloses a technology in which aerial flow, carrying the flying toner particles created by the cleaning device, is supplied to the cyclone separator, and the flying toner particles are separated from the aerial flow to be recovered by a collection box, and the aerial flow is exhausted through the filter.
Still further, Patent Document 4 discloses a technology, in which aerial flow, carrying the flying toner particles created by the developing device and the cleaning device, is sent to a cyclone separator.
Patent Document 1: Unexamined Japanese Patent Application Publication 04-223484:
Patent Document 2: U.S. Pat. No. 7,428,398;
Patent Document 3: Unexamined Japanese Patent Application Publication 08-194422; and
Patent Document 4: Unexamined Japanese Patent Application Publication 2006-91585.
Concerning the productivities of the image forming apparatuses, the technologies disclosed in Patent Documents 2-4 are more effective than the technology disclosed in Patent Document 1. Because, by the cyclone separators of Patent Documents 2-4, the air flow, carrying the flying toner particles, is introduced in a cyclone main body in a tangential direction, whereby the flying toner particles are separated from the air by the swirl flow, and toner particles are collected into the collection box from a lower section of the cyclone main body. Accordingly, the toner particles, carried by the air flow, moving to the filter from the cyclone separator, are extremely reduced in quantity, and the filter tends not to be clogged.
However, according to the technologies disclosed in Patent Documents 2-4, the cyclone separators are fixed into the image forming apparatuses, so that the toner particle collection boxs and the filters have to be separated from the image forming apparatuses for cleaning. During the separating work, the toner particles tend to drop from the connecting sections between the cyclone separators, or the filters.
Further, to fix the cyclone separator within the apparatus may be effective to separate the toner particles in the cyclone separator, however, the toner particles actually and adversely adhere to the inner surface of the cyclone separator, so that, the toner particles accumulate in the cyclone separator and air channels.